PROJECT SCHEDULING

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PROJECT SCHEDULING

•  Projects Vs. Conventional Manufacturing
•   
• Project Scheduling Techniques
• Identifying Critical Paths
• The Critical Path Method
• Crashing and Simulating

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PROJECTS VS. CONVENTIONAL MANUFACTURING SERVICE

• Projects are complex, one-of-a kind
  ,non-repetitive operations
• Building construction
• Engineering design
• Marketing
• New software installation
• Projects have a beginning, a list of interrelated
  tasks, and (one hopes) an end

3
WORK BREAKDOWN STRUCTURES

• To identify all elements of a project, a work
  breakdown structure breaks down the big picture
  into component tasks

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PROJECT MANAGEMENT

• Since many different but interdependent tasks
  need to be performed on a project . . .
• A project team is formed with members from
  different functional areas
• The project manager's job is to plan and
  coordinate the different tasks
• Project scheduling techniques enable the project
  manager to plan, identify, and monitor the
  project's most critical tasks

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PROJECT SCHEDULING TECHNIQUES

• The first step in project scheduling is to
• Identify each task i
• Estimate its duration ti
• Determine the precedence among the tasks
• This information can be represented in 'network'
  form
• Nodes represent activities/tasks (Activity on
  Node)
• Arcs represent precedence among tasks
• Activity A is a predecessor of activity B
• Activity B is a successor of activity A

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NETWORK DIAGRAMS
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IDENTIFYING CRITICAL TASKS

• The project manager needs to know
• The earliest possible finish time for the project
  
• The "critical path" of activities whose delay
  would delay the entire project
• How much slack time exists for each non-critical
  activity
• To answer these questions, the project manager
  must determine the following times for each
  activity
• ESi -- early start time -- earliest time activity
  i can be started
• EFi -- early finish time -- earliest time
  activity i can be finished
• LSi -- late start time -- latest time activity i
  can be started without delaying the project
• LFi -- late finish time -- latest time activity i
  can be started without delaying the project

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THE CRITICAL PATH METHOD

• The Critical Path Method (CPM) is an algorithm
  used to identify these times
• 1) Assign a time (usually 0) to the ES of the
  first activity
• 2) The forward pass. Proceeding from left to
  right through the project network, determine ES
  and EF as follows

• Where "pred(i)" All immediate predecessors of
  activity i

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CPM THE FORWARD PASS
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CPM THE FORWARD PASS
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CPM THE FORWARD PASS
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CPM THE FORWARD PASS
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CPM THE FORWARD PASS
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CPM THE FORWARD PASS
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CPM THE FORWARD PASS
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THE CRITICAL PATH METHOD

• The earliest finish time for the project has now
  been identified.
• A backward pass is necessary to identify the
  critical tasks
• 3) set LF EF for the last activity
• 4) The backward pass. Proceeding from right to
  left through the network, determine LS and LF as
  follows

• Where succ(i)" All immediate successors of
  activity i

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CPM THE BACKWARD PASS
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CPM THE BACKWARD PASS
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CPM THE BACKWARD PASS
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CPM THE BACKWARD PASS
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CPM THE BACKWARD PASS
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CPM THE BACKWARD PASS
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CPM THE BACKWARD PASS
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THE CRITICAL PATH

• We may now find the total slack of each activity
  using either early or late start and finish times
• Activities with no slack are on the critical path

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CRASHING, PROBABILITIES, AND SIMULATING

• "Crashing" is a technique which shows the
  potential gain of investing in reducing the time
  needed for a critical path
• Yields time-cost tradeoff graph
• Another technique exists which replaces each time
  estimate with a probability distribution
• Project evaluation and review technique (pert)
• A more realistic probabilistic approach involves
  simulating project networks